The purpose of the study is to determine the therapeutic effectiveness of long-term single dosage alternate day oral Prednisone in myasthenia gravis. One hundred patients with myasthenia gravis confirmed by electromyographic studies who do not function normally with the use of anticholinesterase drugs will be candidates for this study. Patients will be grouped according to the type of myasthenia gravis and duration of the disease. All patients in the study will receive the therapy, assisted respiration when indicated, and nasal gastric feedings as necessary. One group will receive 100 mg. of Prednisone orally on alternate days; the other group will receive placebo capsules. The code will be broken in any individual patient if significant deterioration occurs. Each patient will be followed for a period of one year and various parameters will be assessed. Muscle strength graded by per cent of loss and functional ability will be assessed by the neurologists. Respiratory muscle strength will be assessed by maximal static respiratory pressures. The effect of Prednisone on the neuromuscular junction will be evaluated by periodic electromyographic examinations. Delayed hypersensitivity as determined by the cutaneous response to various antigens will be studied. This study will extend over a two year period. Finally, speech studies will also be done.